Tiny beads found all over the Moon could supply astronauts with water

The Moon holds more water than we thought in its interior, according to research published today, meaning humans could one day make the most of it as a space resource.

The study looked at a substance found on the Moon called pyroclastic deposits, which are made mostly of volcanic glass beads formed during ancient explosive eruptions. In the past, these have been thought of as potentially useful sources for elements like iron and titanium.

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Now we have reason to believe they also contain water, that could be extracted by astronauts on the Moon.

Our Moon formed as the result of a giant impact with Earth, billions of years ago. This was a very high energy and high temperature process, and it is hard to envision how water could have survived it.

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Because of this, it had been presumed that the interior of the Moon would have little water in it. But that view started to change in 2008 when professor Alberto Saal of Brown University studied volcanic glass beads brought back from the Moon by the Apollo mission, finding trace amounts of water.

The biggest question was whether or not these glass beads were representative of the interior of the Moon, or if they just happened to contain water in an otherwise dry body.

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Now researchers have used satellite data to study more of the Moon’s surface, and found water-rich deposits spread across it. "By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or Luna missions,” said Ralph Milliken, from Brown University, lead author of the study.

“The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet."

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The presence of water on the Moon, and water in the deep interior in particular, is important because it tells us something about the fundamental processes that occurred during the formation of the Moon, and the earliest days of our solar system.

Milliken Lab / Brown University

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“The water somehow had to survive this process or, and perhaps more likely, the water was delivered to the Earth-Moon system by water-rich asteroids and comets after the impact event but before the Moon had completely cooled down and solidified,” Milliken told WIRED.

To determine how much water is in a planet or moon, astronomers use spectrometers to measure the light that bounces off the planetary surface. By looking at the wavelengths of light absorbed or reflected by a surface, scientists can work out which compounds are present. This was made trickier on the Moon, because its surface is warmed during each day.

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Milliken says the most exciting part of this discovery is the potential use for humans. “The amount of water in a given glass bead is not very much, but the pyroclastic deposits are huge, so you have a lot of material to work with,” he told WIRED.

“Water is heavy and expensive to carry with you from Earth, so any water that can be extracted at the lunar surface is a huge help for developing a sustained presence beyond Earth.”